1. Field of the Invention
The present invention generally relates to marine propulsion devices and, more particularly, to an outboard motor which has an opening formed in the cowl and a mechanism that enables the flow of air into the cavity of the cowl to be controlled.
2. Description of the Prior Art
Those skilled in the art of marine propulsion systems are familiar with many different types of outboard motor designs, including many different types of cowls used to cover and protect the internal combustion engine of the outboard motor and its related components.
U.S. Pat. No. 4,722,709, which issued to Irwin et al. on Feb. 2, 1988, describes a marine propulsion device cowl assembly. The marine propulsion device comprises a propulsion unit including a rotatably mounted propeller and an engine drivingly connected to the propeller. A cowl assembly encloses the engine. The cowl assembly has an interior and includes a bottom wall having therein an opening, and a chimney extending upwardly from the bottom wall for conducting air from the opening to the interior of the cowl assembly.
U.S. Pat. No. 4,734,070, which issued to Mondek on Mar. 29, 1988, describes marine propulsion device air intake system. The device comprises a propulsion unit including a rotatably mounted propeller and an engine drivingly connected to the propeller and including an air intake. It also comprises a cowl assembly surrounding the engine and including a front located adjacent the air intake and a rear including an air inlet. It comprises a baffle for isolating air from the engine and for conducting the air around the engine from the air inlet to the air intake.
U.S. Pat. No. 6,302,749, which issued to Tawa et al. on Oct. 16, 2001, describes an outboard motor that has a first case member and a second case member connected to the first case member to form an enclosure having an inner space in which is mounted an engine. The first case member has an air intake hole for taking air into the inner space and a vent hole for exhausting the air after it circulates in the inner space to cool the interior of the inner space. An alternator is disposed in the inner space of the enclosure and has a hollow casing, air passage holes formed in the hollow casing, and cooling fans for drawing air from the air passage holes into the hollow casing to cool the alternator. A cover member is disposed in the inner space of the enclosure and covers at least a portion of the alternator. The cover member has a vent hole communicating with the vent hole of the first case member, an upper wall, a side wall extending from the upper wall and surrounding the portion of the alternator, and air passage holes formed in the side wall for introducing air there through into the cover member and through the air passage holes of the alternator hollow casing to cool the alternator before the air is discharged from the vent hole of the cover member. An electric equipment box is disposed in the engine room at a position intermediate the air intake hole of the engine cover and the alternator.
U.S. Pat. No. 5,573,436, which issued to Trudeau et al. on Nov. 12, 1996, describes a semi-submersible outboard motor cover with an air passage. The improved cover is intended for use with outboard motors. A particular embodiment of the cover is formed by a generally hollow shell having an open side. An air passage is located opposite the open side at an upper portion of the shell. A baffle extends from an upper inner portion of the shell to an elevation below the air passage and is disposed generally opposite the air passage. An exit port is provided at the bottom of the chamber for discharging water collected therein and a valve is provided within the exit port. When the exit port is submerged, the valve is closed and provides a barrier to water entry. Preferably, the cover is located at an upper forward portion of the outboard motor cowl and the both the air passage and air inlet are high up on the upper forward portion.
U.S. Pat. No. 5,052,353, which issued to Dunham, et al. on Oct. 1, 1991, describes a marine propulsion devise cowl assembly. A marine propulsion device comprises a lower unit, a propeller shaft rotatably supported by the lower unit and adapted to support a propeller, an engine supported by the lower unit and drivingly connected to the propeller shaft and a cowl assembly surrounding the engine and including a lower cover member having an upper end, an upper cover member having a lower end, a seal located between the upper end and the lower end, and interengaging mechanisms on the seal and on one of the upper and lower cover members for securing the seal to the one of the upper and lower cover members.
U.S. Pat. No. 4,860,703, which issued to Boda et al. on Aug. 29, 1989, discloses a cowl assembly with water resistant air intake duct and sealing.
The outboard marine motor is housed by a cowl assembly having an upper cowl section and a lower cowl section and includes various features for improving the structural integrity of the cowl assembly and for providing a water-resistant seal at the joint between the cowl sections and at various points of entry of cables and other mechanical devices. An improved air intake duct prevents the entry of water into the interior of the cavity of the cowl assembly. The air intake duct is disposed in an air intake opening provided in the top rear portion of the upper cowl section. The duct includes a bottom wall, a pair upstanding side walls connected thereto, and an upstanding back wall extending between the side walls.
U.S. Pat. No. 6,413,131, which issued to Phillips et al. on Jul. 2, 2002, disclosed an airflow system for an outboard motor. The outboard motor is provided with an air duct located within the cavity of a cowl of an outboard motor. The air duct defines a chamber within it in association with first and second openings that allow heated air to flow, through the creation of convection currents, out of the engine compartment under a cowl. This convection flow removes heat from the fuel system components and reduces the likelihood that “vapor lock” will occur subsequent to the use of the internal combustion engine that is followed by turning the engine off.
U.S. Pat. No. 6,056,611 which issued to House et al. on May 2, 2000, discloses an integrated induction noise silencer and oil reservoir. An oil reservoir is used as a sound attenuator in an outboard motor and is placed under the cowl of the outboard motor with the throats of the engine's throttle bodies disposed between the oil reservoir and the engine itself. This allows the sound emanating from the throttle bodies to be attenuated by the oil reservoir which is cup-shaped to partially surround the throat of the throttle bodies. A plate member can be attached to a hollow wall structure in order to enclose a cavity therebetween. The structure therefore serves as an oil reservoir for the engine and also as a sound attenuating member.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
It is well known that certain openings are provided in cowl structures for the purpose of allowing air to flow from the region surrounding an outboard motor toward the internal cavity within the cowl structure surrounding an internal combustion engine. This airflow, from outside the outboard motor, provides two important functions. It allows additional air to be directed to the throttle body structure at the air intake of the engine, when the engine is operating at high speed, and it also allows cooler ambient air to be directed to the region surrounding the engine and its associated components. The introduction of cool ambient air removes heat from the engine and allows the operating temperature of the engine to be more accurately controlled.
It would be significantly beneficial if a system could be provided that allows the flow of ambient air into the region within the cowl structure in a manner that is more accurately controlled as a function of a preselected operating condition of the engine. The operating condition of the engine can be its operating speed or, alternatively, the operating temperature of the engine.